The invention deals with a n-channel storage FET having at least one gate, namely a floating storage gate which is surrounded on all sides by an insulator. The recharging of the storage gate is effected by channel injection which injects electrons, i.e., recharging by electrons which are strongly accelerated in their own conductive channel and are thereby heated and which, on account of their heating, by means of an electrical field acting in the source-drain direction, overcome the energy threshold to the conductivity band of the insulator and thus reach the storage gate. The channel injection is employed for the programming, and thus the charging of the storage gate so that following this charging, the storage gate exerts a restricting force upon the source-drain path by means of its negative charge which influences the source-drain current.
U.S. application Ser. No. 750,860 now U.S. Pat. No. 4,087,795 has already stated that with a storage FET of this type, in the unprogrammed state the channel is of the depletion type. It is also stated in U.S. application Ser. No. 750,860 now U.S. Pat. No. 4,087,795 that the storage FET can consist of an additional, controllable control gate which possesses a terminal and which exerts a capacitive influence upon the storage gate. The storage FET is provided in particular for program stores of a telephone exchange system.